List of Major League Baseball pitchers who have thrown an immaculate inning

In baseball, a strikeout occurs when a pitcher throws three strikes to a batter during his time at bat.[1] An immaculate inning occurs when a pitcher strikes out all three batters he faces in one inning, using the minimum possible number of pitches—nine.[2] Ninety-three different pitchers have struck out three batters on nine consecutive pitches in a half-inning of a Major League Baseball (MLB) game as of September 2019, the most recent being Will Harris of the Houston Astros on September 27, 2019. Seven have accomplished the feat more than once in their career, and no player has ever struck out four batters on twelve pitches in an inning.[3][4][5][6] John Clarkson was the first player to strike out three batters on nine pitches, doing so in the third inning for the Boston Beaneaters against the Philadelphia Quakers on June 4, 1889.[7]

Lefty Grove, Sandy Koufax (left), Nolan Ryan, Randy Johnson, Chris Sale, Max Scherzer (right), and Kevin Gausman are the only pitchers to achieve an immaculate inning on two separate occasions, with Koufax accomplishing the feat three times.

Of the 93 pitchers who have accomplished the feat, 71 were right-handed and 22 left-handed. Eight of these (including five active pitchers) have played for only one major league team. Four—Bob Gibson, Randy Johnson, Pedro Martínez and Nolan Ryan—are also members of the 3,000 strikeout club.[8] Sloppy Thurston, Ryan, Wade Miley, and Thomas Pannone are the only rookies to have attained the milestone.[9][10][11][12] Ryan struck out three batters on nine pitches in the American League and National League, becoming the first player to achieve the feat in both.[13] Danny Jackson is the sole player to pitch an immaculate inning in the World Series.[14]

Of the 23 players eligible for the Baseball Hall of Fame who pitched an immaculate inning, 13 have been elected and five were elected on the first ballot.[15] Players are eligible for the Hall of Fame if they have played in at least 10 major league seasons and have either been retired for five seasons or deceased for at least six months.[16] These requirements leave 26 players ineligible who are active, four who are living and have played in the past five seasons, and eight who did not play in 10 major league seasons.